An electric storage element disclosed in JP 2012-43564 A includes insulation covers that respectively cover collector tabs located on both sides of an electrode assembly. The electric storage element disclosed in JP 2002-231297 A includes a foamed-resin sheet inserted in a gap between the electrode assembly and a casing.
However, because made of a resin, the insulation cover disclosed in JP No. 2012-43564 A needs to have a certain thickness. For this reason, the insulation cover restricts the size of the electrode assembly and thereby decreases an electric capacity. Further, since the insulation cover covers the entire area of the collector tab, injection property (easiness in injecting) when an electrolytic solution is injected into the interior of the casing is decreased. A foamed-resin sheet in JP 2002-231297 A is arranged entirely on the lower area of the electrode assembly. Therefore, a gap is not formed between the lower portion of the electrode assembly and the bottom surface of the casing. This decreases the injection property.